Hard candies, otherwise known as hard boiling candies, traditionally have been prepared from a mixture of saccharose and glucose syrup; water is evaporated from the mixture and the resulting concentrated mass is formed into candies by mold casting or by use of a candy forming apparatus, such as a drop roller machine. The hard candy which results has a "glass like" appearance and low surface tack or stickiness; however, saccharose and glucose syrup are known to be cariogenic, and also cause an almost immediate increase in blood sugar levels after ingestion. Therefore, it has been desired to replace saccharose and glucose syrup with sugar substitutes which are less harmful to the teeth, which do not cause as sharp an increase in blood sugar levels, which are sweeter, or which are absorbed slower from the digestive tract so as to not cause as great an increase in weight as ingestion of equal quantities of glucose.
Sugar alcohols, such as sorbitol, mannitol, maltitol, and xylitol, are polyols, and are important sugar substitutes. Sorbitol, mannitol, and maltitol are considerably less sweet than saccharose, and xylitol has about the same sweetness as saccharose. The sugar alcohols are converted to fructose after ingestion, which does not require insulin to facilitate its entry into the cells; while the metabolism of fructose does require insulin, this step wise metabolism results in a damping out of the peaks in blood sugar levels which result from ingesting saccharose or glucose.
Studies have shown about a 30% reduction in dental carries in rats on sorbitol and mannitol diets, and virtually complete elimination of carries in rats when on xylitol diets. Therefore, it is highly desirable to produce candies containing xylitol and other sugar alcohols. (For more information on sweeteners, and sugar alcohols in particular, see pp. 917-922 of the Van Nostrand Reinhold Encylopedia of Chemistry, 4th Ed., edited by Considine, New York, 1984.) All patents, articles, or other printed information mentioned herein is incorporated by reference as if reproduced in full hereinbelow, inclusive of Finnish Patent Application 905133.
Attempts have been made to produce candies formed primarily of xylitol. For example, Finish Patent No. 61,265, corresponding to Great Britain Patent No. 1,583,573 discloses the production of hard caramels by adding 10%-30% by weight of powdered xylitol to a xylitol melt while the melt is maintained at a temperature not substantially exceeding xylitol's melting point of 93.degree. C.-95.degree. C.; the xylitol powder can be added to the xylitol melt at temperatures below the melting point of xylitol, provided that a melt is still present. The powdered xylitol used is limited to powder with an average particle size of about 40 microns to 150 microns. The mixture of xylitol powder with the xylitol melt is poured into small forms corresponding in shape and size to the desired caramels. However, the process is not continuous, and it is technically difficult to realize, so that the process is not well suited for industrial production of candy. Further, the resulting candies do not have the desired textural qualities, such as low tack, and good dimensional stability of the candy shape. This is believed to be due to the candy being comprised primarily of xylitol, which does not provide suitable physical characteristics to the candy when used in such high proportions.
Finish Patent Application No. 885,397, corresponding to published European Patent Application No. 0,370,761, discloses the production of hard confectionery products containing 45%-65% by weight xylitol, which are produced by heating a mixture containing 5%-20% by weight of xylitol, 85%-70% by weight maltitol or lactitol, less than 15% by weight of other sugar alcohols, and small amounts of water, to a temperature ranging from 170.degree. C. to 175.degree. C., allowing the melt to cool to a temperature between 105.degree. C. and 120.degree. C., and subsequently rapidly adding 30%-60% powdered xylitol by weight of the final hard confectionery composition while mixing and rapidly cooling the mixture. The molten sugar alcohols can also be combined with the powdered xylitol at temperatures below 90.degree. C. or below 65.degree. C,. and the mix is then shaped or rolled. The resulting product is highly hygroscopic, and the candies do not maintain their shape (have poor dimensional stability) and are perishable.
Finish Patent No. 61,392, corresponding to Great Britain Patent No. 2,526,020, notes that xylitol has poor tableting characteristics, since tablets made by pressing grains of xylitol together are too soft and friable. However, by dry blending xylitol with another polyol, such as sorbitol, and a tableting lubricant, such a calcium or magnesium stearate, stable tablets are formed. However, the dried tablets do not have the glass like confectionery texture of hard candies, and are not a homogenous mixture at the molecular level, being a dry blended mixture of grains of xylitol and another sugar alcohol.
Generally, when xylitol is used to prepare candy, a problem is presented by the inability to treat a xylitol melt with a traditional roller machine; this is primarily due to xylitol's inability to crystallize satisfactorily. Further, hard boiling candies formed from a mixture containing xylitol combined with other sugar alcohols, are usually extremely hygroscopic and sticky.
Thus, there is a need for hard candies formed of xylitol combined with other sugar alcohols, which can be formed using traditional drop roller machines or other traditional forming equipment and which are not hygroscopic and sticky. Further, there is a need to produce hard candies containing xylitol mixed with other sugar alcohols which maintain their shape.
Therefore, it is a primary object of the present invention to prepare hard candies containing xylitol and other sugar alcohols which maintain their shape and have low tack.
It is a further object of the present invention to form hard candies containing xylitol combined with other sugar alcohols which can be worked into the desired shape by conventional means.